Case unstacker



June 18, 1968 J. A. JOHNSON 3,383,817

CASE UNSTACKER Fiied March 17, 1966 5 Sheets-Sheet 1 INVENTOR. Ja/m liJo/msan 'ATTY.

June 18, 1968 J. A. JOHNSON 3,388,817

CASE UNSTACKER Filed March 1'7, 1966 5 Sheets-Sheet 2 INVENTOR. 63 0/0/27: IZJa/msan June 18, 195 J. JOHNSON 3,388,817

CASE UNSTACKER Filed March 17, 1966 5 Sheets-Sheet 5 INVENTOR. John Eda/mama w 0 BY June 18, 1968 JOHNSON 3,388,817

CASE UNSTACKER Filed March 17, 1966 5 Sheets-Sheet 4 'llllll rip! 1 INVENTOR. da/zrz lZz/a/IHSOIZ June 18, 1968 J. A. JOHNSON 3,388,817

CASE UNSTACKER Filed March 17, 1966 5 Sheets-Sheet 5 s r'c' INVENTOR. Jo/m fldalmson United States Patent ()lfice Faiented June 18, 1968 3,38%,817 CASE UNSTAtZKER John A. Johnson, Milford, Ghio, assignor to Cedar dates, Inc, Cincinnati, Ohio, a corporation of Ohio Filed Mar. 17, 1966, Ser. No. 535,187 8 Claims. (Cl. 2ll4-3.5)

This invention relates to case uns'tacking devices and is particularly directed to a completely automatic apparatus controlled by the movements of cases or stacked cases upon a continuously operated conveyor.

An object of the invention is to provide a greatly simplified, compact and reliable device adapted to unstack case's received in stacked condition at a rapid rate and in timed relation with a single, continuously moving case conveyor.

Another object of the invention is to provide in a case un-stacker, a vibratile means automatically operable during the unstacking operation to detach the lowermost case fro-m a stack in the event said case is wedged to a. case in the stack next above it.

A further object of the invention is to provide an automatically controlled case unstacker which will permit a single case entering it to be moved through it in a normal case conveyed manner.

A still further object of the invention is to provide novel interconnected controls for the automatic operation of a case unst-a-cking device having the foregoing characteristics.

Other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings, wherein:

FIG. 1 is a fra-gmental, end elevational view of the unstacker in a position to discharge the last case of a stack and to receive the next succeeding stack of cases.

FIG. 2 is a fragmental, front elevational view of the unstacker shown in FIG. 1.

FIG. 3 is a section on line 33 of FIG. 2.

FIG. 4 is a fragmental, rear elevational View of the unstacker shown in FIG. 1.

FIG. 5 is a section taken on line 55 of FIG. 4.

FIG. 6 is an enlarged section taken on line 66 of FIG. 4.

FIG. 7 is an enlarged section taken on line 7- 7 of FIG. 1.

FIG. 8 is a schematic diagram showing the fluid pressure and electrical control circuits. for the unstacker illustrated in FIGS. 1-7 of the drawings.

In general, this invention comprises an unstacker which straddles a continuously operable conveyor 21 that is commonly located in the floor 22 of a dairy plant, or the like; said conveyor being adapted to move single cases or stacked cases to and through a gated entrance portion 23 into the unstacker Zti. The unstacker 20 performs the function of intermittently detaching the lowermost case from the stack and permitting each of said cases to be moved on the conveyor out of the unstacker and through the exit portion 24 thereof. When a stack has been separated and discharged, one at a time, at the exit side, the next stack of cases will be moved by the conveyor through the entrance portion for the next unstacking operation.

The unstacker 20 comprises a frame 25 having vertical members 26 joined together by suitable horizontal bracing members 27 to form a rigid body that is adapted to straddle the conveyor 21. Within the frame there is positioned a case stack receiving housing having front and rear Walls 28 and 29, respectively, and an end Wall 30 at the exit end of the unstacker which has an opening 31 at its lower end large enough to permit discharge of a single case therethrough; said casing being completely open at its entrance end to receive a stack of cases moved therethrough on the conveyor 21.

As best shown in FIGS. 1, 4 and 6 an intermittently ope ated stack elevator 32 is disposed on the rear side of the unstacker frame and comprises a vertically reciprocated pad 33 normally in position to engage the side of a case that is second from the bottom in a stack resting upon the conveyor within the unstacker. The pad is adapted to lift the stack a distance sufficient to disengage the lowermost case in the stack from the second from the bottom case therein and after movement of the lowermost case out of the destacker to then move downwardly to normal retracted position and to that end the pad 33 is preferably actuated by :a double acting, pneumatic cylinder 34 that is pivotally mounted on the frame 25 by a bracket 35 and has its piston rod 36 pivotally connected to the pad by means of a pin 37 passed through the rod clevis 38 and through opposed bearing blocks 3939 bolted to the pad. The lower end of a floating link 40 is welded to the central part of the pin 37 and has a notched central portion 41 to clear the rod clevis 38. The upper end of the floating link is pivotally connected to the lower end of a lever 42 by means of a pin 43 mounted between two bearing blocks 4444 secured to the floating link, said lever end being welded, or otherwise connected, to the central part of said pin 43. The lever is rockably mounted on the frame by a single bearing block 45 secured centrally to the lever and disposed between two bearing blocks 4646 mounted on :a brace 47 fixed on the frame 25, a pivot pin 48 being fixed in the blocks 46-46 and rotatable in the :link mounted block 45. The upper end of the lever 42 is biased outwardly by an expansile spring 49 positioned on the frame by a headed bolt 50 that is threaded in the frame and passes through the spring and a slot 51 formed in the top of the lever 42. A polystyrene case engaging cover 52 is preferably secured to the pad 33 and an opening 53 is formed in the rear wall 29 of the unstacker housing to permit actuation of the case stack elevator by the cylinder 34 that is shown as disposed outside of said housing. A set bolt 54 is threaded through the cylinder clevis 38 and is adapted to engage the pad 33 to maintain said pad in substantially vertical retracted position.

With particular reference to FIG. 6 the full line showing of the case stack elevator indicates its normal, retracted condition while the dotted lines therein depict the positions of the various elevator parts at the top of the case stack elevating function, it being particularly noted that the pivoted connection between the floating link 4% and the spring biased lever 42 provides a toggle device that continuously urges the pad 33 toward engagement with the case stack under a predetermined pressure while the pivotal connection between the pad 33, the toggle device and the piston rod 36 on the pivotally mounted cylinder 34 synchronizes case engagement of the pad with the elevating and retracting motions of the cylinder. A

pair of rub plates 55-55 are positioned on the inside of the front wall 28 of the housing opposite the elevator device so that the case stack will slide against them when the elevator is operative.

Now referring to FIGS. 1, 2 and 6 of the drawings, there is shown a case stack lowerator 56 located On the front side of the unstacker frame 25 and comprising a double acting, pneumatic cylinder 57 swingably mounted at its upper end on a hangar 58 depending from a frame brace 2'7. A piston rod 59 depends from the lower rod so of the cylinder 57 and has a case stack engaging and lowering finger 6-1 fixed on its lowermost end, said finger extending througn a vertical slot 62 formed in the rear wali 23 of the housing and guided for vertical reciprocating movement between a pair of spaced angle irons 63- 63 welded to the exterior of the housing on opposite sides of the slot 62.

As best shown in FIG. 6 of the drawing a laterally disposed, lowerator conditioning means in the form of a double acting pneumatic cylinder 64 is pivotaly mounted at one end on a bracket 65 carried upon a table 66 that is in turn positioned on a cross brace 67 of the frame 25. The free end of the piston rod 68 for the cylinder 64 is pivotally connected to a yoke 69 fixed on the rod end 60 of the pneumatic cylinder 57 the yoke also carrying a switch block 70 that is adapted to engage, and actuate a switch LS4 for the control purposes to be described hereinafter. As indicated by full lines in PEG. 6 the case stack lowerator is normally in lateral position to lower the stack after the lowermost case has been carried from the unstacker on the conveyor 21 while the dotted line positions of the stack lowerator shows the parts in position for retracting and raising the finger to its uppermost position, the broken lines showing the finger in its position to contact the next lowermost case in the stack.

The gated entrance portion 23 for the unstacker has the conveyor 21 extending through it over a zig-Zag portion 210 (FIG. 3), the stacked case travel thereover being guided by opposed side rails 71 and 72. A gate,

generally indicated by the reference numeral 73, is located at the entrance to the zigzag portion and comprises an arm 74 pivotaly mounted on a vertical pin 75 fixed on the side rail 71, and having a case contacting bar '76 fixed on its free end. A double acting, pneumatic cylinder 7 is pivotally mounted to the frame on a clevis 78, the piston rod 79 of the cylinder being pivoted to a bracket 80 on the arm. Actuation of the cylinder in one direction locates the bar 76 in the path of the oncoming stacks of cases on the continuously moving conveyor 21 and as the bar 76 is momentarily moved out of the path of the stacks upon actuation of the cylinder in the opposite direction, movement of the stack through the zigzag portion cants said first stack to permit return of the bar 76 to block the path of the succeeding stack of cases thereby allowing the stacks to enter the unstacker one at a time in response to each operating cycle of the cylinder 77. In FIG. 4 of the drawings there is shown a vertically extending stack guide plate 81 hinged at 8282 to the entrance end of the side wall 29 of the unstacker housing, said guide plate being swung between an operative case guiding position partially closing the open end of the housing and an inoperative housing open position by a double acting, pneumatic cylinder 83 pivotally mounted at one end on a frame mounted bracket 84. The piston rod 85 of the cylinder has its clevis 86 pivotally connected to a bracket 87 fixed on the guide plate 81.

As has been specified a switch LS4 is opened and closed by movement of the laterally acting cylinder 64- controlling the position of the case stack lowerator 56. A switch LS1 (FIG. 3) is mounted on the guide rail 72 of the entrance portion 23 and has an operating arm 88 positioned to be engaged by a case stack as it begins its exit from the zigzag entrance portion 210; said arm being elongated downstream in order that the stack will continue to engage it until the said stack just approaches its unstacking position within the frame 25.

A case sensing switch LS3 has a vertically movable actuating arm 89 located in the conveyor 21 in position to be depressed by a case that is in position within the frame 25, said arm extending a distance downstream into the exit side 24 of the unstacker.

With reference to FIGS. 1, 6 and 7 of the drawings there is shown a stack sensing switch LS2 which is located on the outside of the end wall 3% of the housing at a height to be engaged by the second from the bottom case in the stack. The switch LS2 is actuated by a blade 94 pivotally mounted at 91 on a bracket 92; said blade extending through a slot 93 formed in the end wall 3% and bearing on its outside edge against a switch actuating 'o1ler 4 FIG. 7).

Operation- With particular reference to PEG. 8 of the drawings-it is understood that the controls are all shown in normal positions conditioning the unstacker to accept a stack of cases moving along the conveyor 21 toward the unstacking device 26. It will be noted that the stack sensing switch LS2 is in position to open the line to a solenoid actuated, spring returned selector valve V2 that controls the pneumatic cylinder 83 for the stack guide plate 31 andv said switch LS2 also closes the line to a solenoid actuated, spring returned selector valve V1 forthe pneumatic cylinder 77 that operates the entrance gate arm 74, the track entrance switch LS1 being interposed in said linev and in normally closed condition. A stack of cases will therefore pass by the opened entrance gate arm 74 and proceed through the zigzag portion of the entrance track and then open the switch LS1 which'will de-energize selectorvalve V1 and cause cylinder 77 to close the gate arm 74 against entrance of the next succeeding stack of cases.

Because of the length of the arm 88101 the switch LS1 the stack of cases will maintain the said switch LS1in open position until the case stack sensing switch LS2 is operated by the stack whereupon switch LS1 will return to closed position but the stack actuated position of switch LS2 will hold the line to valve V1 in open condition so long as a stack of cases is in the unstacker.

When the stack sensing switch LS2 is actuated a line to the valve V2 is closed thereby closing the stack guide plate 81 on the stack within the frame. The stack sensing switch LS2 also closes the line to the trackpositioned switch LS3; switch LS3 being simultaneously closed by the lowermost case in the positioned stack. The closing of switch LS3 energizes a solenoid actuated, spring returned selector valve V3 for the lowerator conditioning means which operates pneumatic cylinder 64 to-swing the stack lowering finger 61 to retracted position when the finger is in its normal lowermost position beneath the level of the conveyor (FIGS. 1 and 2). As the finger 61 is moved by cylinder 64to retracted position the switch LS4 is closed which simultaneously energizes solenoid actuated, spring returned selector valves V4 and V5. Energization of valve V4 operates the normally retracted case stack elevator cylinder 34 to engage the next to the bottom case and push the stack of cases upwardly away from the lowermost case on the conveyor to free the said case from beneath the stack which then moves down the conveyor. At the sametime the elevator is operative the valve V5 operates the pneumatic cylinder to elevate the finger 61 to its uppermost position under the stack held in raised position by the elevator. As the free case moves out of the unstacker on the conveyor it permitsswitch LS3 to open thereby operating the lowerator conditioning pneumatic cylinder 64 to return the finger 61 to case engaging position under the stack-which movement opens switch LS4 to return valves V4 and V5 to normal positions whereby the elevator cylinder is retracted and the cylinder 57 is operated to lower the stack onto the conveyor. As soon as the stack being lowered rests upon the conveyor switch LS3 is again closed and the unstacking operation described heretofore is repeated over and over again until the last case in the stack'disengages the stack sensing switch LS2 which will return the controls to'normal conditions opening gate entrance arm 81 for the next case unstacking operation. f

In the event only a single case would inadvertently enter the unstacker it would open the switch LS1 and operate cylinder 77 to close the gate entrance arm 74 behind it. However,'it would not operate case stack sensing switch LS2 norswitch LS3 and therefore the single case would pass out through the unstacker on the conveyor after closing switch LS1 and opening the entrance gate arm '74 to admit the next succeeding stack of cases.

When the lowermost case in astack being unstacked sticks to the case next above it switch LS3 will be momentarily opened thus closing switch LS4 and retracting the elevator, thus lowering the stack on switch LS3 to close said swtich to then raise the elevator. The alternate raising and lowering of the stack elevator in rapid succession will usually shake the lowermost case loose from the stack and allow said lowermost case to be moved on the conveyor out of the exit side and automatically restoring the unstacking operation on the remainder of the cases in the stack.

What is claimed is:

1. In a case unstacker a continuously operating conveyor, a frame straddling the conveyor and adapted to receive a stack of cases, a case stack elevator on the frame adapted to engage the second from the bottom case in the stack during operation of the elevator, intermittently operated means for raising and lowering the elevator, a case stack lowerator 0n the frame adapted to engage the second from the bottom case in the stack during operation of the lowerator, intermittently operated power means for lowering and raising the lowerator, conditioning means connected to the lowerator and adapted to actuate the lowerator between a stack engaging and a stack retracted position, a two-position control means operated by the conditioning means and having an initial position simultaneously lowering the elevator and lowering the lowerator and a second position simultaneously raising the elevator and raising the lowerator, a conveyor positioned switch adapted to sense the presence of the lowermost case in the stack, and means actuated by the conveyor positioned switch operating the conditioning means.

2. A case unstacker as set forth in claim 1 characterized by the fact that the case stack elevator is a normally retracted and vertically reciprocated grip means biased toward engagement with the second from the bottom case in the stack.

3. A case unstacker as set forth in claim 2 further characterized by the fact that the grip means is a pad, said pad being biased toward engagement with the second from the bottom case in the stack by a spring pressed toggle means mounted on the frame.

4. A case unstacker as set forth in claim 1 characterized by the fact that the case stack lowerator comprises an operating finger and the conditioning means has a power means adapted to actuate the finger.

5. In a case unstacker a continuously operating conveyor, a frame straddling the conveyor and adapted to receive a stack of cases, an elevator on the frame, intermittently operating means for raising and lowering the elevator, grip means on the elevator adapted to engage the second from the bottom case in a stack during operation of the elevator, a case stack lowerator on the frame, a finger on the lowerator adapted to engage the second from the bottom case in the stack during operation of the lowerator, laterally acting means connected to the finger of the lowerator, and adapted to reciprocate the lowerator finger between operative and retracted positions, a twoposition control means operated by the laterally acting means and having an initial position simultaneously raising the elevator and raising the lowerator and a second position simultaneously lowering the elevator and operating the lowerator, a conveyor positioned switch adapted to sense the presence of the lowermost case in the stack, means actuated by the'conveyor positioned switch initiating operation of the laterally acting means, and a stack sensing switch on the frame adapted to energize the conveyor positioned switch.

6. A case unstacker as set forth in claim 5 characterized by the fact that the laterally acting means is a reversible motor, the two-position control means is a switch, and the conveyor positioned switch has an actuating arm adapted to be depressed by the bottom case in the stack when disposed upon the conveyor.

7. In a case unstacker a continuously operating conveyor, a frame straddling the conveyor and adapted to receive a stack of cases, a stack entrance portion on the conveyor upstream from the frame, a normally closed gate for the entrance portion, a case stack elevator on the frame adapted to engage the second from the bottom case in the stack during operation of the elevator, a case stack lowerator on the frame adapted to engage the second from the bottom case in the stack operation of the lowerator, laterally acting means connected to the lowerator and adapted to reciprocate the lowerator between a stack engaging position and a retracted position, a two position control means operated by the laterally acting means and having an initial position simultaneously raising the elevator and raising the lowerator and a second position simultaneously lowering the elevator and operating the lowerator, a two-position conveyor located switch adapted to sense the presence and absence of the lowermost case in the stack, means actuated by the conveyor positioned switch initiating operation of the laterally acting means, a case stack sensing switch on the frame adapted to energize the conveyor positioned switch, and control means adapted to open the gate when the stack sensing switch is deenergized.

8. In a case unstacker as set forth in claim 7 characterized by the fact that the stack entrance portion of the conveyor has a zig-zag configuration to cant the stack moving therethrough, and the gate is a laterally acting bar that closes normally between the canted case stack and the succeeding case stack on the conveyor.

References Cited UNITED STATES PATENTS 3/1965 Schmid 2148.5 6/1967 Burns et a1 214- XR UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,388 ,817 June 18 1968 I John A. Johnson It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 25, after "stack" insert during Signed and sealed this 14th day of October 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR. 

5. IN A CASE UNSTACKER A CONTINUOUSLY OPERATING CONVEYOR, A FRAME STRADDLING THE CONVEYOR AND ADAPTED TO RECEIVE A STACK OF CASES, AN ELEVATOR ON THE FRAME, INTERMITTENTLY OPERATING MEANS FOR RAISING AND LOWERING THE ELEVATOR, GRIP MEANS ON THE ELEVATOR ADAPTED TO ENGAGE THE SECOND FROM THE BOTTOM CASE IN A STACK DURING OPERATION OF THE ELEVATOR, A CASE STACK LOWERATOR ON THE FRAME, A FINGER ON THE LOWERATOR ADAPTED TO ENGAGE THE SECOND FROM THE BOTTOM CASE IN THE STACK DURING OPERATION OF THE LOWERATOR, LATERALLY ACTING MEANS CONNECTED TO THE FINGER OF THE LOWERATOR, AND ADAPTED TO RECIPROCATE THE LOWERATOR FINGER BETWEEN OPERATIVE AND RETRACTED POSITIONS, A TWO POSITION CONTROL MEANS OPERATED BY THE LATERALLY ACTING MEANS AND HAVING AN INITIAL POSITION SIMULTANEOUSLY RAISING THE ELEVATOR AND RAISING THE LOWERATOR AND A SECOND POSITION SIMULTANEOUSLY LOWERING THE ELEVATOR AND OPERATING THE LOWERATOR, A CONVEYOR POSITIONED SWITCH ADAPTED TO SENSE THE PRESENCE OF THE LOWERMOST CASE IN THE STACK, MEANS ACTUATED BY THE CONVEYOR POSITIONED SWITCH INITIATING OPERATION OF THE LATERALLY ACTING MEANS, AND A STACK SENSING SWITCH ON THE FRAME ADAPTED TO ENERGIZE THE CONVEYOR POSITIONED SWITCH. 